w w w . j m r t . c o m . b r
Availableonlineatwww.sciencedirect.com
Original
Article
Eco-friendly
recycled
polypropylene
matrix
composites
incorporated
with
geopolymer
concrete
waste
particles
Flávio
James
Humberto
Tommasini
Vieira
Ramos
a,∗,
Raphael
Henrique
Morais
Reis
a,
Iryna
Grafova
b,
Andriy
Grafov
b,
Sergio
Neves
Monteiro
aaMilitaryInstituteofEngineering-IME,Prac¸aGeneralTibúrcio,80,22290-270,Urca,RiodeJaneiro,RJ,Brasil
bUniversityofHelsinki,DepartmentofChemical,KumpulaCampus,A.I.Virtasen,aukio1,P.O.Box55FI-00014,Helsinki,FI,Finland
a
r
t
i
c
l
e
i
n
f
o
Articlehistory: Received1May2019 Accepted14January2020 Availableonlinexxx Keywords: Geopolymerwaste Recycledpolypropylene Eco-friendlycomposites Waterabsorption Tensilepropertiesa
b
s
t
r
a
c
t
Civil constructionwasteshave beenincorporated intopolymers forrecycling as novel engineering composites. In the present work eco-friendly composites with recycled polypropylene(rPP)matrixincorporatedwithgeopolymerconcretewasteparticles,wither plain(GCW)orsurface-modifiedwitholeicacid(AGC)wereinvestigated.Thegeopolymer concretewasteparticlesweremixedwithpolymerpowdertoprovideaneffectivedispersion betweenthedifferentmaterials.Compositeswereproducedbyaninitialreactiveextrusion processingfollowedbyinjectionmolding.Thesenovelcompositeswithamountof20,40 and50wt%ofGCWparticles,bothplainas-receivedandsurface-modified,weretechnically evaluated bytensiletests,statisticallyanalyzed byANOVA,aswellasbywater absorp-tionasperASTMstandards.Surfacedispersionofnanoparticleswasrevealedbyatomic forcemicroscopy.Microstructuralanalysiswasperformedbyscanningelectronmicroscopy. TheresultsindicatedthatthesesustainableGCWparticlesincorporatedintorPPmatrix exhibitsuperiorprocessabilityandwaterabsorptionlessthan0.01%.TherPP/AGC compos-itespresentrelativelyhigherelasticmodulus,629MPa,ascomparedtotheneatrPP,with 529MPa.Thesepropertiessuggestpotentialsustainableapplicationsinbuilding construc-tionusingwastematerials.
©2020PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).
1.
Introduction
Theconstructionindustryis,inpastyears,investigating inno-vativematerialstosubstitutetraditionalones,suchaswood, polymers, concrete and metals [1]. In particular, polymer matrixcompositesarereplacingconventionalmaterialsowing
∗ Correspondingauthor.
E-mail:[email protected](F.J.Ramos).
tointrinsic characteristicssuchaslowdensity and plastic-ity. Among these composite those reinforced with natural fibers composea classofsuccessful materialsincreasingly usedinbuildingconstructions[2–5].Itisworthmentioning that,withinthisclass,nanocelluloseisapromising reinforce-mentforpolymercompositeswithspecialproprieties[6–17]. Inadditiontonaturalfibers,wastesfrombuilding construc-tion incorporatedinto polymermatricesconstitute another importantclassofeco-friendlycompositeswithspecific recy-clingpurpose[18,19].
https://doi.org/10.1016/j.jmrt.2020.01.054
2238-7854/©2020PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/ licenses/by-nc-nd/4.0/).
Pleasecitethisarticleinpressas:RamosFJ,etal.Eco-friendlyrecycledpolypropylenematrixcompositesincorporatedwithgeopolymerconcrete Intermsofthermoplastics,polypropylene(PP)isoneofthe
mostimportantpolymers,producedinlargescaleand com-monlyappliedatseveralsectors,includingtextile,automotive, laboratory equipment, plastic parts and reusable contain-ers.However,itshugepost-consumedvolumehasgenerated worldwide large amounts of urban solid residues. On the otherhand,importantcharacteristicssuchashighchemical stability,stiffness,hardness,toughness,heatresistanceand mechanicalpropertiesstillremaininspentPP,makingitan attractiverecycledwastetobeuseashighperformance com-positematrix[20–23].Indeed,severalworksinvestigatedthe applicationofinorganicfillersinPPmatrixcomposites.Sha etal.[24]investigatedinnovativemethodsoffiller modifica-tionintheproductionofthermoplasticcompositesenabling the increase of the strength, stability of interface bond-ing,highdispersionofparticles andappropriatedrheology. PedrazzoliandPagoretti[25]reportedonthepropertiesofPP compositesreinforcedwithexpandedgraphitenanoplatelets. Zhai et al. [26] investigatedthe recycling asbestos tailings used asfillers inPP composites. Ahmedaet al.[27] inves-tigated the influence of filler loading on the properties of polypropylene/marble sludge compositesand reportedthat the performance of the polymer composites depends on the relationship between the interfaces ofthe matrix and fillers.Chenetal.[28]studiedthe solubilityand diffusivity ofCO2 in polypropylene/micro-calcium carbonate
compos-ites.Theeffectsofthefillersandinterfacebondingcondition betweenthefillersandpolymermatrixwerereportedbythe authors. Etcheverry et al. [29] studied the effect of adhe-sionandmechanicalpropertiesthroughchemicalanchorage ofpolypropylene onto glass fibers, previously treated with methylaluminoxane.Zhuetal.[30]observedtheinfluenceof themontmorilloniteonmechanicalproperties,crystallization andrheologicalbehaviorsofPPcomposites.
Aninnovativematerialdevelopedtoreplaceconventional cementinbuildingconstructionisthegeopolymer,produced fromachemicalreactionofsilica(SiO2)andalumina(Al2O3)
toformaninorganicpolymerbygeopolymerization[31–33].In fact,geopolymershavegainedconsiderableattentionowing totheirintrinsiccharacteristicssuchasfireresistance,high toughnessandlowerCO2emissionsduringproductivecircle,
ascomparedtoPortlandcement[34].Geopolymerscanalso beusedincompositematerials.Ferdousetal.[35]observed theinfluenceofgeopolymerfillersintheproductionofhybrid composites,suchastheredmud,flyashand asbestos tail-ings.As acivil construction cement, ageopolymers might beincorporatedwithadditivessuchassandand pebblesto makeconcrete[36].Duringconstructionandafterdemolition, geopolymerconcretesmaybecomewastesandthuscouldbe recycledbyadditionasasecondphasetoapolymermatrix.A similarsituationmayalsooccurwithaPPproduct,whichafter operationallifebecomesawaste.Inthiscase,theeasytomold thermoplasticPPcouldberecycledascompositematrix.Based ontheaforementionedresults,theobjectiveofthisworkwas toevaluatetheprocessabilityandthetensilebehavioraswell astoperformamicrostructuralanalysisofeco-friendly com-positeswithincorporationofoleic-acidmodifiedgeopolymer concrete(AGC)waste particlesinto therecycled
polypropy-lene(rPP).ForthefirsttimeAGCwasteisincorporatedintoa recycledpolymertodevelopasustainablenovelcomposite.
2.
Materials
and
methods
2.1. Materials
Theplaingeopolymerconcretewaste(GCW),anas-received material, was supplied by Lafarge Concreto Ltda., Brazil. Recycledpolypropylene(rPP),fromproductsmoldedbyblow processingwassuppliedbyCOMBRAREComercialBrasileira deReciclagemLtda.Theoleicacid(99%purity)wassupplied bySigmaAldrich,Brasil.RecycledPPcompositeincorporated withbothplainas-receivedGCWparticlesandoleicacid sur-facemodified(AGC)particleswereinvestigated.
2.2. Materials
Theas-receivedGCWwascrushedinparticlessmallerthan 270meshandtreatedwitholeicacidduring24h,asreported elsewhere[18].ThemodifiedparticlesofAGCweredispersed intomoltenrPPmatrixinascrewextruder.Thetemperature profile,startingfromthefeedingzoneuptothedie,was180, 190and200◦C,whilethescrewrotatingratewasmaintained at6rpm[37].TheproportionsproducedofrPP/AGCcorrespond to80/20,60/40,50/50(m/m%).Pelletsofthemodified compos-iteswereprocessedinaBattenfeldinjectionmachine,Plus35 model.Theblendmixtureswereperformedat200◦C. Accord-ingtoASTMC272[38]andASTMD638[39]standards,water absorptionandtensilepropertieswereevaluated,respectively. Theinfluenceofthemodifierfillerswasobservedduringthe processingoftheAGCspecimens,showinggreaterfluidityand lowtorque,aswellasbettermoldingandprocessabilityfor theAGCcomposites,independentlyoftheamountprocessed. Insteadofwhatwasexpected,ahigherfluiditywasacquired byincreasingtheproportionofmodifiedgeopolymerconcrete into thepolymermatrixoftheAGCcomposites.Thiseffect canbeexplainedbytheplasticizinginfluenceoftheoleicacid fixedonthesurfaceofthehybridfillers,whilewasblended intotherPPmatrix[40].
Atomicforcemicroscopy(AFM)wasperformedto evalu-ate theagglomeratedandsurfaceconditionofthepolymer composites.ObservationwascarriedonaXE7equipment, pro-ducedbyParkSystem.
Water absorptionevaluationasperASTM C272[38]was performedtoevaluatethepercentageofwaterabsorptionin therPPaswellasinbothrPP/GCWandrPP/AGCcomposites, consideringtheresultsofsevenspecimensforeach.
TensiletestsasperASTMD638[39],werecarriedouton auniversalmodel1185Instronmachine.Theelastic modu-lus (between0.05%and0.25%strains)atacrossheadspeed of5.105mm/min,andtensilestrengthatthesamecrosshead speed,oftherPP/AGCcompositeswerecalculated.Analysisof variance(ANOVA)wasperformedforstatisticalvalidationof thepropertiesobtainedfromtentensile-testedspecimensof eachtypeofcomposites,includingtherPP(0%AGC).
Fig.1–(a)Elasticmodulus;(b)tensilestrength,and(c)maximumdeformationvariationwithrecycledpolypropylene(rPP) compositesincorporatedwitholeicacidmodifiedgeopolymerconcretewaste(AGW).
Table1–Waterabsorption(wt%)ofinjectionmolded recycledpolypropylene(rPP)compositesincorporated withplaingeopolymerconcretewaste(GCW)andoleic acidmodifiedgeopolymerconcretewaste(AGC).
FractionofAGC Incorporation(wt%) rPP/GCW rPP/AGC 0 0.01 ≤0.01 20 ≤0.01 ≤0.01 40 ≤0.01 ≤0.01 50 ≤0.01 ≤0.01
3.
Results
and
discussion
Table 1 presents the results of water absorption tests for purerPP,0%geopolymerconcretewaste,aswellasforboth rPP/GCWandrPP/AGCcomposites.Accordingtotheseresults, all investigated materials absorbed practically no amount (≤0.01%) ofwater, what corroborates previous results [18]. They also indicate no significant effect of capillary water absorptionbygeopolymerconcreteincorporatedintothePP
matrix,whichrevealsconsistentlyembeddedplainGCWand modifiedAGCintorPP.
ThetensilepropertiesoftherPP/AGCcompositespecimens and therPPmatrix (0%AGC) arepresentedinTable2.The observedresultsshowthe influenceofthe highamountof modifiedAGC fillersintothematrix.Tensileresultsforthe rPP/GCW composites were less significant for this present investigation and,therefore, are notpresentedherein. The goodinteractionbetweenmodifiedAGCandrPPenablesthe increaseoftheelasticmodulusofthecompositesbythe incor-poration of modified geopolymer concrete waste particles. Furthermore,theresultsshowthattherPPmatrixdecreasethe maximumdeformationfrom42.7%toabout24%,stabilizing thislevelatthe40–50%AGCproportions.Theincreaseofthe elasticmodulusisanindicativeofagoodadhesionbetween matrix/fillers.Consequently,thecompositesacquiredsuitable stiffness capacityfor civil construction applications. These resultscorroborates thosealready obtainedforPP incorpo-ratedindustrialwastes[26,27,29].
Fig. 1 shows the graphs corresponding to the results presentedinTable2.Asforthevariationoftheelastic
mod-Table2–Tensilepropertiesofrecycledpolypropylene(rPP)compositesincorporatedwitholeicacidmodifiedgeopolymer concretewaste(AGC).
FractionofAGCincorporation(wt%) TensileStrength(MPa) ElasticModulus(MPa) MaximumDeformation(%)
0 33.5±1.6 529.1±33.9 42.7±2.6
20 26.8±1.4 534.1±25.3 34.6±3.6
40 22.0±0.8 618.2±31.2 24.6±0.8
Pleasecitethisarticleinpressas:RamosFJ,etal.Eco-friendlyrecycledpolypropylenematrixcompositesincorporatedwithgeopolymerconcrete
Fig.2–SEMfractographyofrecycledpolypropylene(rPP)compositesincorporatedwitholeicacidmodifiedgeopolymer concretewaste(AGC)inconditionsofpreviousextrusion(a),(c)(e);andfinalinjectionmolded(b),(d),(f).
Fig.3–Atomicforcemicroscopyofrecycledpolypropylene(rPP)compositesincorporatedwith:(a)20wt%and(b)50wt%of oleicacidmodifiedgeopolymerconcretewaste(AGC).
Table3–Analysisofvariance(ANOVA)parametersfor tensilepropertiesofrecycledpolypropylene(rPP) compositesincorporatedwitholeicacidmodified geopolymerconcretewaste(AGC).
AnovaParameters F Fc P
TensileStrength 161.32 3.01 4.88×10−16
ElasticModulus 12.04 3.01 5.25×10−5 MaximumDeformation 109.18 3.01 4.00×10−14
ulus, Fig. 1(a) reveals a significant increase in the elastic modulusabove20%incorporationofoleicacidsurface treated-geopolymerconcretewaste.Thiscorrespondstoaneffective reinforcementinthestiffnessofrPP/AGCcomposites.By con-trast, the tensile strength, Fig. 1(b), and maximum (total) deformation,Fig.1(c),sufferadecreasewithAGC incorpora-tion.Thereasonfortheseadverseresultsinthestrengthand deformationmightbeattributedtogeneration ofcracks as furtherdiscussedregardingthemicrostructuralevolution.
ThedatapresentedinTable2andshowninFig.1were validatedbyANOVA.Table3presentsthevaluesoftheANOVA parametersF,Fcritical(Fc) andP.Inthistable,considering that5%(0.05)isthelevelofsignificance,valuesofF>Fcare associatedwith95%ofconfidenceinthedifferencebetween them.Moreover,ifP<0.05,asignificantdifferencemightbe consideredbetweenvalues.
AsshowninTable3,basedontheANOVA,the incorpora-tionofmodifiedAGCintorPPcausesastatisticallysignificant increaseintheelasticmodulus.Inotherwords,the hypothe-sisthatthevaluesarethesamecanberejectedwith95%of confidence.
Fig.2showsSEMfractographsof20,40and50%AGC incor-porated into rPP composites, each one in both processing conditionsofinitiallyextruded,Fig.2(a),(c)and(e),andfinally moldedbyinjection,Fig.2(b),(d)and(f).Theinitiallyextruded conditionrevealsafractureassociatedwithmoreporesthen thefinallyinjected.Thisclearlyindicatesthatthesecondstage ofinjectionprocessinghassignificantlydecreasedthe poros-ity, mainlyfor50% AGC compositeingoing from extruded condition,Fig.2(e),tomold-injected,Fig.2(f).Itconfirmsan effectiveencapsulatingofthegeopolymerconcretewaste par-ticles by the recycled polypropylene matrix. This porosity elimination afterinjectioncorroborates thepractically null waterabsorptionresultsinTable1.Ontheother hand,the injectedspecimensdisplayevidenceofcracksaspointedfor the40and50% AGCcompositesinFig.2(d)and(f), respec-tively.Thiscrackingobservationcouldexplainthedecreasein strengthandtotaldeformationinTable2andFig.1.
Fig.3showsAFMresultsfortwoinvestigatedextreme con-ditionsofrPPcomposites,with20and50%AGC.Thisfigure evidencesthechangeinroughness,fromarelativelysmother surfaceforthe20%AGCcompositeinFig.3(a)toarougher surfaceforthe50%AGCinFig.3(b).Actually,thecauseof sur-faceroughnessforthe50%AGCcompositemightbeassigned totheagglomerationofoleicacidmodifiedgeopolymer con-cretewastenanoparticles,aspointedbyarrowsinFig.3(b). TheresultsinFig.3disclosethesignificantinfluencethatAGC particlespromoteinthecompositesurfacetopography.As dis-cussed,theresultsinFig.2forthe50%AGCcompositeindicate aneffectiveencapsulatingcondition,whichshouldbe
inter-pretedasgood adhesionbetweenparticles andrPPmatrix. Thisisapparently confirmedbythewell matrix-embedded AGC particles pointed in Fig.3(b), whichcertainly favorsa stiffnessreinforcementpresentedinTable2anddepictedin
Fig.1(a).
4.
Summary
and
conclusions
• Eco-friendlycompositeswithrecycledpolypropylene(rPP) matrixincorporatedwith20,40and50wt%ofgeopolymers concretewasteparticles,bothplainas-received(GCW)and oleicacidsurface-treated(AGC)wereforthefirsttime pro-cessedandcharacterized.
• Aninitialextrusionfollowedbyinjectionmoldingresultin rPP/AGCcompositesdisplayinggreaterfluidityin associa-tionwithlowextrusiontorqueaswellasimprovedmolding ifcomparedwithrPP/GCWcomposites.
• Practicallynowaterabsorption(≤0.01%)wasfoundforboth typesofrPP/GCWand rPP/AGC composites,includingfor purerPP.
• The incorporation of AGC particles above 20wt% signif-icantly increases the elastic modulus of the rPP matrix. However, this incorporation reducesthe tensile strength andtotalstrain.
• SEMfratographsrevealedaneffectivereductionof poros-ityduringprocessingfromextrusiontoinjectionmolding, whichjustifythenullwaterabsorption.However,cracking aftermoldingwouldberesponsiblefordecreaseinstrength andstrain.
• AFMdiscloses evidence ofrougher surface due to parti-clesagglomerationincompositewithhighamountofAGC, whichmightfavortheobtainedstiffnessreinforcement.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Acknowledgements
The authors thank the Conselho Nacional de Desenvolvi-mento CientíficoeTecnológico(CNPq)andCoordenac¸ão de Aperfeic¸oamentodePessoaldeNívelSuperior(CAPES)for sup-portingthiswork.
r
e
f
e
r
e
n
c
e
s
[1]GemertDV,CzarneckiL,ŁukowskiP,KnapenE.Cementand concretecomposites.Cementconcreteand
concrete–polymercomposites:Twomergingworlds:Areport from11thICPICCongressinBerlin.CementConcrete Compos2005,
http://dx.doi.org/10.1016/j.cemconcomp.2005.05.004. [2]DiBellaG,FioreV,GaltieriG,BorsellinoC,ValenzaA.Effects
ofnaturalfibresreinforcementinlimeplasters(kenafand sisalvs.Polypropylene).ConstrBuildMater2014;58:159–65.
[3]SinghB,GuptaM,TarannumH,RandhawaA.Natural fiber-basedcompositebuildingmaterials.In:KaliasKaithBS,
Pleasecitethisarticleinpressas:RamosFJ,etal.Eco-friendlyrecycledpolypropylenematrixcompositesincorporatedwithgeopolymerconcrete KaurI,editors.Cellulosefibers:bio-andnano-polymer
composites.Berlin,Germany:Springer;2011.p.701–20.
[4] SinghB,GuptaM.Naturalfibercompositesforbuilding applications.In:MohantyAK,MisraM,DrzalLT,editors. Naturalfibers,biopolymers,andbiocomposites.BocaRaton, USA:CRC;2005.
[5] PalPK,RanganathanSR.Juteplasticcompositesforthe buildingindustry.PopPlast1986;31:22–4.
[6] IlyasRA,SapuanSM,IbrahimR,AtikahMSN,AtiqahA, AnsariMNM,etal.Production,processesandmodificationof nanocrystallinecellulosefromagro-waste:areview. IntechOpen;2019.p.3–32,
http://dx.doi.org/10.5772/intechopen.87001.
[7] IlyasRA,SapuanSM,IbrahimR,AbralH,IshakMR,Zainudin ES,etal.Sugarpalm(Arengapinnata(Wurmb.)Merr) cellulosicfibrehierarchy:acomprehensiveapproachfrom macrotonanoscale.JMaterResTechnol2019;8(3):2753–66.
[8] HalimatulMJ,SapuanSM,JawaidM,IshakMR,IlyasRA. Effectofsagostarchandplasticizercontentonthe propertiesofthermoplasticfilms:mechanicaltestingand cyclicsoaking-drying.Polimery2019;64(6):422–31.
[9] HalimatulMJ,SapuanSM,JawaidM,IshakMR,IlyasRA. Waterabsorptionandwatersolubilitypropertiesofsago starchbiopolymercompositefilmsfilledwithsugarpalm particles.Polimery2019;64(9):595–603.
[10]IlyasRA,SapuanSM,IshakMR,ZainudinES.Sugarpalm nanofibrillatedcellulose(Arengapinnata(Wurmb.)Merr): effectofcyclesontheiryield,physic-chemical,
morphologicalandthermalbehavior.IntJBiologMacromol 2019;123:379–88.
[11]AbralH,AriksaJ,MahardikaM,HandayaniD,Aminah, SandrawatiN,etal.Transparentandantimicrobialcellulose filmfromgingernanofiber.FoodHydrocoll2020;98:105266,
http://dx.doi.org/10.1016/j.foodhyd.2019.105266.
[12]IlyasRA,SapuanSM,AtiqahA,IbrahimR,AbralH,IshakMR, etal.SugarPalm(Arengapinnata[Wurmb.]Merr)starch filmscontainingsugarpalmnanofibrillatedcelluloseas reinforcement:waterbarrierproperties.PolymCompos 2019:1–9,http://dx.doi.org/10.1002/pc.25379.
[13]AtigahA,JawaidM,SapuanSM,IshakMR,AnsariMNM,Ilyas RA.Physicalandthermalpropertiesoftreatedsugar palm/glassfibrereinforcedthermoplasticpolyurethane hybridcomposites.JMaterResTechnol2019;8(5):3726–32.
[14]IlyasRA,SapuanSM,IbrahimR,AbralH,IshakMR,Zainudin ES,etal.Effectofsugarpalmnanofibrillatedcellulose concentrationsonmorphological,Mechanicalandphysical propertiesofbiodegradablefilmsbasedonagro-wastesugar palm(Arengapinnata(Wurmb.)Merr)starch.JMaterRes Technol2019;8(5):4819–30.
[15]IlyasRA,SapuanSM,IshakMR.Isolationand
characterizationofnanocrystallinecellulosefromsugar palmfibres(ArengaPinnata).CarbohydPolym
2018;181:1038–51.
[16]IlyasRA,SapuanSM,SanyangML,IshakMR,ZainudinES. Nanocrystallinecelluloseasreinforcementforpolymeric matrixnanocompositesanditspotentialapplications:a review.CurrAnalChem2018;14(3):203–25.
[17]IlyasRA,SapuanSM,IshakMR,ZainudinES.Effectof delignificationonthephysical,thermal,chemical,and structuralpropertiesofsugarpalmfibre.BioResources 2017;12(4):8734–54.
[18]RamosFJHTV,MendesLC,CestariSP.Organicallymodified concretewastewitholeicacid.JThermalAnalCalorim 2015;119(3):1895–904.
[19]ShokriehMM,KefayatiAR,ChitsazzadehM.Fabricationand mechanicalpropertiesofclay/epoxynanocompositeandits polymerconcrete.MaterDesign2012;40:443–52,
http://dx.doi.org/10.1016/j.matdes.2012.03.008.
[20]SwolfsY,ZhangQ,BaetsJ,VerpoestI.Theinfluenceof processparametersonthepropertiesofhotcompacted self-reinforcedpolypropylenecomposites.ComposPartA ApplSciManuf2014;65:38–46,
http://dx.doi.org/10.1016/j.compositesa.2014.05.022.
[21]MazovIN,IlinykhIA,KuznetsovVL,StepashkinAA,ErginKS, MuratovDS,etal.Thermalconductivityof
polypropylene-basedcompositeswithmultiwallcarbon nanotubeswithdifferentdiameterandmorphology.JAlloys Compounds2014;586:S440–2,
http://dx.doi.org/10.1016/j.jallcom.2012.10.167.
[22]MinaMF,SeemaS,MatinR,RahamanMJ,SarkerRB,Gafur MA,etal.Improvedperformanceofisotactic
polypropylene/titaniumdioxidecomposites:effectof processingconditionsandfillercontent.PolymDegrad Stability2009;94:183–8.
[23]ModestiM,LorenzettiA,BonD,BescoS.Effectofprocessing conditionsonmorphologyandmechanicalpropertiesof compatibilizedpolypropylenenanocomposites.Polymer 2005;46:10237–45.
[24]ShahAR,LeeDW,WangYQ,WasyA,HamKC,JayaramanK, etal.EffectofconcentrationofATHonmechanical propertiesofpolypropylene/aluminiumtrihydrate(PP/ATH) composite.TransNonferrousMetSocChina2014;24:s81–9,
http://dx.doi.org/10.1016/S1003-6326(14)63292-1.
[25]PedrazzoliD,PegorettiA.Expandedgraphitenanoplatelets ascouplingagentsinglassfiberreinforcedpolypropylene composites.ComposPartAApplSciManuf2014;66:25–34,
http://dx.doi.org/10.1016/j.compositesa.2014.06.016. [26]ZhaiW,WangY,DengY,GaoH,zLin,Lim.Recyclingof
asbestostailingsusedasreinforcingfillersinpolypropylene basedcomposites.JHazardMater2014;270:137–43,
http://dx.doi.org/10.1016/j.jhazmat.2014.01.052. [27]AhmedakK,RazaNZ,HabibF,AijazM,AfridiMH.An
investigationontheinfluenceoffillerloadingand compatibilizeronthepropertiesofpolypropylene/marble sludgecomposites.JIndustEngChem2013;19:1805–10,
http://dx.doi.org/10.1016/j.jiec.2013.02.024.
[28]ChenJie,LiuTao,YuanWei-kang,ZhaoLing.Solubilityand diffusivityofCO2inpolypropylene/micro-calciumcarbonate composites.JSupercritFluids2013;77:33–43,
http://dx.doi.org/10.1016/j.supflu.2013.02.007.
[29]EtcheverryM,FerreiraMJ,CapiatiN,BarbosaS.Chemical anchorageofpolypropyleneontoglassfibers:effecton adhesionandmechanicalpropertiesoftheircomposites. InternJAdhesionAdhesives2013;43:26–31,
http://dx.doi.org/10.1016/j.ijadhadh.2013.01.006. [30]ZhuS,ChenJ,ZuoY,LiH,CaoY.
Montmorillonite/polypropylenenanocomposites: mechanicalproperties,crystallizationandrheological behaviors.ApplClaySci2011;52:171–8,
http://dx.doi.org/10.1016/j.clay.2011.02.021.
[31]MajidiB.Geopolymertechnology,fromfundamentalto advancedapplications:areview.MaterTechnol 2009;24(2):79–87.
[32]DuxsonP,Fernández-JiménezA,ProvisJL,LukeyGC,Palomo A,vanDeventerJS.Geopolymertechnology:thecurrentstate oftheart.JMaterSci2007;42(9):2917–33.
[33]DavidovitsJ.Geopolymers:inorganicpolymericnew materials.JThermAnalCalorim1991;37(8):1633–56.
[34]KonstantinosA,Komnitsa.Potentialofgeopolymer technologytowardsgreenbuildingsandsustainablecities. ProcediaEng2011;21:1023–32.
[35]FerdousW,ManaloA,KhennaneA,KayaliO.Geopolymer concrete-filledpultrudedcompositebeams–concretemix designandapplication.CemConcrCompos2015;58:1–13.
[36]HabertG,DeLacaillerieJD,RousselN.Anenvironmental evaluationofgeopolymerbasedconcreteproduction:
reviewingcurrentresearchtrends.JCleanProd 2011;19(11):1229–38.
[37]DennisHR,HunterDL,ChangD,KimS,WhiteJL,ChocJW, etal.Effectofmeltprocessingconditionsontheextentof exfoliationinorganoclay-basednanocomposites.Polymer 2001;42(23):9513–22.
[38]AMERICANSOCIETYFORTESTINGANDMATERIALS. C272/C272M:standardtestmethodforwaterabsorptionof corematerialsforsandwichconstructions.ASTM;2012.
[39]AMERICANSOCIETYFORTESTINGANDMATERIALS.D638: standarttestmethodfortensilepropertiesofplastic.ASTM; 2010.
[40]SanderMM,NicolauA,GuzattoR,SamiosD.Plasticisereffect ofoleicacidpolyesteronpolyethyleneandpolypropylene. PolymTesting2012;31(8):1077–82.